DESCRIPTION: Since the time of the first NINDS-sponsored International Scientific Symposium on Tourette Syndrome (TS), clinicians and basic scientist alike have been challenged with the task of better defining TS and understanding the pathophysiology of this disorder. The overall purposes of both the First and Second International Scientific Symposia on TS were to stimulate new research and improve care for patients with this disorder, and, as such, both were tremendously successful. The investigator proposes, therefore, a Third International Symposium to specifically address the following topics: issues of rating scales and data concerning the natural course of TS, a review of recent studies of co-morbid conditions, neuropathological examinations of TS brain, review of comparison data of specific cognitive tasks with sensitive neuroimaging measures of brain activity, the pharmacotherapeutic interventions for TS, and examination of new research data concerning non-pharmacologic treatments for this disorder.